Members of Collier's family joined city officials and lawmakers from Somerville for the event in the governor's office on Friday. Patrick signed the bill privately last month shortly after it was approved by the Legislature.

Collier, a Winchester native, was fatally shot April 18 while sitting in his police cruiser. Authorities said he was attacked by the two suspects in the April 15 Boston Marathon bombings that killed three people and wounded more than 260 others.

Before his death, Collier had been offered a job with the Somerville police and his family said he was looking forward to joining the force.